The ability to define the location of airway obstructions in Obstructive Sleep Apnea (OSA) patients is critical for surgical and oral appliance treatments because these therapies target the manipulation or removal of specific collapsible oropharyngeal regions. Yet, to this date, there are no adequate tools that can accurately and conveniently locate the collapse site. Current methods are either inaccurate or invasive whereby catheters are placed deep in the pharynx for prolonged periods of time making these studies uncomfortable and unpopular. We propose to develop an easy to apply non-invasive device that can be worn during the night, which can localize, for the first time, airway instability in the natural asleep state. The proposed, Nighttime Acoustic Pharyngometer (NAP) device, is based on the principle of acoustic reflectance whereby the distance to an obstruction can be determined from the time it takes a sound wave to travel to that obstruction and back. The device consists of an oral mask embedded with speaker / microphone connected to a sleep monitor. The sleep monitor will collect sound reflections along with the patient's sleep status, which will allow it to analyze sound reflections with and without airway obstructions. Signal processing will then extract those echoes caused by the obstruction and consequently calculate the distance to collapse site. We plan to use an oral mask as the basis for the patient interface because the oral cavity offers a more efficient transfer of sound into the airways when compared to the narrow and bifurcated nasal passage. The patient interface will be connected to a CPAP to provide heated humidification typically required for oral breathing. We will also adjust the CPAP pressure repeatedly during the night, in a manner identical to CPAP titration, as a method to improve overall system accuracy. Resolution of apneas during CPAP titration multiple times during the night will afford NAP a unique environment to pinpoint obstruction-specific echoes and to enhance localization accuracy. Furthermore, this will allow NAP to be easily integrated within the standard sleep laboratory operation, which will minimize technologists training and speed adoption by physicians. This Phase I will focus on developing and testing the patient interface, modify a CleveMed sleep monitor for this application and test on the bench and on patients. We believe NAP will provide the sleep community, for the first time, with an important and convenient complementary tool to help direct surgical or oral appliance treatments for OSA patients. PUBLIC HEALTH RELEVANCE: The ability to define the location of airway obstructions in Obstructive Sleep Apnea (OSA) patients is critical for surgical and oral appliance treatments because these therapies target the manipulation or removal of specific collapsible oropharyngeal regions. Yet, to this date, there are no adequate tools that can accurately and conveniently locate the collapse site. Current methods are either inaccurate or invasive whereby catheters are placed deep in the pharynx for prolonged periods of time making these studies uncomfortable and unpopular. We propose to develop an easy to apply non-invasive device that can be worn during the night, which can localize, for the first time, airway instability in the natural asleep state. The proposed, Nighttime Acoustic Pharyngometer (NAP) device, is based on the principle of acoustic reflectance whereby the distance to an obstruction can be determined from the time it takes a sound wave to travel to that obstruction and back. The device consists of an oral mask embedded with speaker / microphone connected to a sleep monitor. The sleep monitor will collect sound reflections along with the patient's sleep status, which will allow it to analyze sound reflections with and without airway obstructions. Signal processing will then extract those echoes caused by the obstruction and consequently calculate the distance to collapse site. We plan to use an oral mask as the basis for the patient interface because the oral cavity offers a more efficient transfer of sound into the airways when compared to the narrow and bifurcated nasal passage. The patient interface will be connected to a CPAP to provide heated humidification typically required for oral breathing. We will also adjust the CPAP pressure repeatedly during the night, in a manner identical to CPAP titration, as a method to improve overall system accuracy. Resolution of apneas during CPAP titration multiple times during the night will afford NAP a unique environment to pinpoint obstruction-specific echoes and to enhance localization accuracy. Furthermore, this will allow NAP to be easily integrated within the standard sleep laboratory operation, which will minimize technologists training and speed adoption by physicians. This Phase I will focus on developing and testing the patient interface, modify a CleveMed sleep monitor for this application and test on the bench and on patients. We believe NAP will provide the sleep community, for the first time, with an important and convenient complementary tool to help direct surgical or oral appliance treatments for OSA patients.